1. Field of the Invention
The invention relates to the field of plant breeding and plant biotechnology, in particular to a transgene inserted into genetic linkage with a genomic region of a plant, and to the use of the transgene/genomic region to enhance the germplasm and to accumulate other favorable genomic regions in breeding populations.
2. Description of Related Art
Breeding has advanced from selection for economically important traits in plants and animals based on phenotypic records of the individual and its relatives to the use of molecular genetics to identify genomic regions that contain the valuable genetic traits. Information at the DNA level has lead to faster genetic accumulation of valuable traits into a germplasm than that achieved based on the phenotypic data only. The development of transgenic crops has further revolutionized breeding and agricultural crop production. The outstanding success of genetically engineered crops is evident from the fact that the area of farmland devoted to transgenic crops has grown from a negligible acreage ten years ago to well over half the acreage for major crops in agriculturally important countries such as USA, Canada, Brazil and Argentina. In addition to the development of input traits, plant biotechnology also holds great promise for the future development of output traits that will directly benefit consumers, like nutritionally superior foods, such as the vitamin A enriched rice, unsaturated oils, and agricultural products of medical value to name a few. The potential for commercial success of a transgene encoding a new or improved input or output trait is a great incentive for development of novel transgenes and their deployment through breeding these genes into elite germplasm.
During the development of transgenic crop plants much effort is concentrated on optimization of the insertion and expression of the transgene, and then introgressing the transgene throughout the breeding population by classical breeding methods. The site of insertion of a transgene into the host genome has been a concern for at least two reasons; (i) the region where it inserted may modulate the level of expression of the transgene, and (ii) the insertion of the transgene may disrupt the normal function or expression of a gene near or where it has been inserted. The selection of genomic locations that are beneficial for gene integration provides for suitable levels of stable expression of an introduced gene, or genes, and generally does not negatively affect other agronomic characteristics of the crop plant.
The genomic region in which the transgene has been inserted also provides agronomic phenotypes to the crop plant. These phenotypes have their own value in a breeding program and these regions should be considered when selecting among multiple transgene insertion events. Transgene insertion events into genomic regions that are associated with improved performance with respect to an agronomic trait or multiple trait index result in an improved phenotype in the crop plant and progeny derived from the crop plant that contain the transgene and the associated improved phenotype. Selecting for the transgenic event necessarily results in selecting a segment of the host genome that surrounds it, and the improved phenotypic effect. Further improvements involve the identification of molecular markers for the tracking and maintenance of the genomic segment with the associated transgene. This is an area that has not been adequately addressed in current plant breeding with transgene insertion events.
There is a need in the art of plant breeding to identify genomic regions associated with improved performance with respect to an agronomic trait or multiple trait index that are linked with a transgene insertion event and then select for these transgene-genomic regions for dispersion into the breeding population of the crop. The present invention provides consideration to estimating the value of the genomic region and the transgene event. This value can then be used as a criterion for selecting among multiple transgenic events. A further benefit is that linkage drag around a transgene is minimized and valuable genomic regions are selected that contain the transgene for breeding into the germplasm of a crop.